Difference between revisions of "cpp/string/basic string/at"
From cppreference.com
< cpp | string | basic string
(add example) |
(fmt example, caps) |
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===Return value=== | ===Return value=== | ||
| − | + | Reference to the requested character. | |
===Exceptions=== | ===Exceptions=== | ||
| − | + | Throws {{lc|std::out_of_range}} if {{c|1=pos >= size()}}. | |
===Complexity=== | ===Complexity=== | ||
| − | Constant | + | Constant. |
===Example=== | ===Example=== | ||
| Line 35: | Line 35: | ||
int main() | int main() | ||
{ | { | ||
| − | + | std::string s("message"); // for capacity | |
| − | + | s = "abc"; | |
| − | + | s.at(2) = 'x'; // ok | |
| − | + | std::cout << s << '\n'; | |
| − | + | std::cout << "string size = " << s.size() << '\n'; | |
| − | + | std::cout << "string capacity = " << s.capacity() << '\n'; | |
| − | + | try { | |
| − | + | // throw, even if capacity allowed to access element | |
| − | + | s.at(3) = 'x'; | |
| − | + | } | |
| − | + | catch (std::out_of_range& exc) { | |
| − | + | std::cout << exc.what() << '\n'; | |
| − | + | } | |
} | } | ||
| output= | | output= | ||
Revision as of 13:17, 10 September 2013
| reference at( size_type pos ); |
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| const_reference at( size_type pos ) const; |
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Returns a reference to the character at specified location pos. Bounds checking is performed, exception of type std::out_of_range will be thrown on invalid access.
Contents |
Parameters
| pos | - | position of the character to return |
Return value
Reference to the requested character.
Exceptions
Throws std::out_of_range if pos >= size().
Complexity
Constant.
Example
Run this code
#include <stdexcept> #include <iostream> int main() { std::string s("message"); // for capacity s = "abc"; s.at(2) = 'x'; // ok std::cout << s << '\n'; std::cout << "string size = " << s.size() << '\n'; std::cout << "string capacity = " << s.capacity() << '\n'; try { // throw, even if capacity allowed to access element s.at(3) = 'x'; } catch (std::out_of_range& exc) { std::cout << exc.what() << '\n'; } }
Output:
abx string size = 3 string capacity = 7 basic_string::at
See also
| accesses the specified character (public member function) |
